This paper compares the void ratio obtained in samples prepared by dry and moist tamping, and dry and wet pluviation. These 4 methods are amongst the few other commonly adopted methods used in the preparation of reconstituted sand samples in the laboratory e.g. slurry deposition and vibration. The samples were prepared in 100mm diameter and 200mm long split moulds. The effects of the number of soil layers and the drop height of the tamper, on particle packing, were studied in the tamping method. Microscopic images of these samples showed that the packing was more compact between the interface of two adjacent layers in tamped samples. In the pluviation method, the distance through which the sand particles were rained and the mass-flow were the two investigated parameters. The mass-flow was varied with the use of 3 different funnel openings. Frictional drag because of the air was ignored in the pluviation tests. The dry pluviation results seem to suggest that up to the limiting mass-flow, the funnel...

Every plant synthesizes phytochemicals with different properties to supply a pool of molecules for food, chemical and pharmaceutical applications. Concurrent with “green technology” development, use of green solvents to extract phytochemicals instead of conventional non-eco-friendly solvents is crucial. Hydrotrope is a one of the green solvents that enhances solubility of poorly water-soluble or hydrophobic compounds in aqueous solutions. This article critically reviews the extraction of phytochemicals using various hydrotropic solvents. Hydrotropy mechanisms, factors influencing extraction and recovery methods of phytochemicals were also evaluated in this review.

The use of sand to improve the strength of natural clays provides a viable alternative for civil infrastructure construction involving earthwork. The main objective of this note was to investigate the compressive strength of compacted clay-sand mixes. A natural clay of high plasticity was mixed with 20% and 40% sand (SP) and their compaction and strength properties were determined. Results indicated that the investigated materials exhibited a brittle behaviour on the dry side of optimum and a ductile behaviour on the wet side of optimum. For each material, the compressive strength increased with an increase in density following a power law function. Conversely, the compressive strength increased with decreasing water content of the material following a similar function. Finally, the compressive strength decreased with an increase in sand content because of increased material heterogeneity and loss of sand grains from the sides during shearing.

Using waste rubber tires for concrete production will reduce the demand for natural aggregate and help to reduce environmental pollution. The main challenge of using waste rubber tires in concrete is the deterioration of mechanical properties, due to poor bonding between rubber and cement matrix. This research aims to evaluate the mechanical and thermal properties of rubberised concrete produced by using different proportions of rubber powder and silica fume. Ordinary Portland cement was partially replaced with silica fume by amounts of 5%, 10%, 15% and 20%, while sand was replaced by 10%, 20% and 30% with waste rubber powder. Tests were carried out in order to determine workability, density, compressive strength, splitting tensile strength, elastic modulus, thermal properties, water absorption and shrinkage of rubberised concrete. The compressive strength and splitting tensile strength of concrete produced using waste rubber powder were reduced by 10–52% and 9–57%, respectively. However, the reduction in modulus of elasticity was 2–36%, less severe than compressive and splitting tensile strengths. An optimum silica fume content of 15% was observed based on the results of mechanical properties. The average shrinkage of concrete containing 15% silica fume increased from −0.051% to −0.085% at 28 days, as the content of waste rubber powder increased from 10% to 30%. While the thermal conductivity of rubberised concrete was reduced by 9–35% compared to the control sample. Linear equations were found to correlate the density, splitting tensile strength, modulus of elasticity and thermal conductivity of concrete with silica fume and waste rubber powder.